Decorative, wear-resistant sheets of resinous composition are widely used as surface coverings for a wide variety of products such as floors, walls, counter and table tops, book covers and various containers. Such surfaces can be covered by tiles cut from the sheet or by the sheet itself. In addition, these sheets can be used as fabrics for upholstery, clothing, automobile interiors and the like.
The decoration of these sheets is of great importance in increasing the products' marketability by helping the covering to adapt to a particular use. These coverings are often printed with a design that simulates such things as brick, slate, ceramic tile, wood, leather, etc., or with some other attractive pattern. The methods for producing a decoration on the product are many and varied. One simple method is to print a design with a rotogravure press on a backing and then cover the surface with a transparent resinous coating. Such printed products usually have a protective, transparent coating on the surface which is called a wearlayer. Printed products have the disadvantage that the wearability is determined by the thickness of the wearlayer and the printed design does not have the true appearance of natural occurring material such as stones.
One of the popular floorcoverings produced commercially is made by stenciling onto a base particulate fused vinyl compositions having contrasting pigmentation. The sheet is then consolidated in a large press utilizing high heat and pressure to produce a moulded inlaid product which has multi-colored design elements resulting from the utilization of the fused vinyl compositions of contrasting pigmentation. This process results in an inlaid decoration i.e. the same decoration is present throughout the service life of the product. A major disadvantage of the stencil procedure is the slow speed and extreme care that must be exercised in handling the stencils to produce a product of consistant thickness. Should the stencils be out of alignment, any overlap of different colored granules would result in an excessively thick portion of the sheet. Although both of the two procedures mentioned provide a method for producing a controlled decoration of repeating or definite design, neither produces a design that has a three-dimensional appearance.
One method for achieving a three-dimensional effect is disclosed in U.S. Pat. No. 2,987,102, which issued to A. J. Heinrichs on June 6, 1961. Here, opaque and transparent or translucent chips are blended together and formed into a smooth sheet by the application of heat and pressure, after which a pigmented backing is laminated to the underside of this sheet. As the colored backing is visible through the transparent or translucent areas of the top sheet, the design appears to be three-dimensional. This method is, however, capable of producing only a random, nongeometrical pattern.
A process for producing an inlaid decorative sheet with a geometric decoration of three-dimensional appearance is disclosed in U.S. Pat. No. 3,359,352 which issued to W. H. Powell, et al, on Dec. 19, 1967. In accordance with one of the procedures disclosed in the patent, a layer of fine granules of resinous composition commonly referred to as a dryblend is deposited on the surface of a base, and then heated to form a partial coalescence or sintering of the granules. The sintered layer is then cooled and a design is printed on the surface with a printing composition which will penetrate into the sintered composition. The printed sintered layer is then subjected to heat and, if desired, pressure to form a non-porous layer. The resulting product is a resinous composition sheet which has the printed decoration extending into the sheet. The product can be given a decorative three-dimensional appearance by utilizing transparent or translucent granules. The disadvantage of this procedure is that any given printed area is restricted to a single color, that of the printing composition there applied, and so the product does not have the appearance of having an inlaid design.